The disclosed subject matter relates generally to communication systems and, more particularly, to a system and method for performing echo cancellation balance using noise generator and average power detection.
The traditional telephone network is based on assigning distinct lines or “circuits” to each connected call. When a user lifts a telephone handset and goes off-hook, the local central office provides a dial tone to the caller and assigns a “circuit” to him or to her. Once the desired number has been dialed, the call is switched to one or more intermediary central offices before finally reaching the destination. The Public Switched Telephone Network (PSTN), or the conventional telephone network as we know it today, relies on the use of circuit-switched connections.
The tremendous growth of the Internet and other computer networks has given rise to a new telephone technology, which is fundamentally different from the traditional PSTN. Known as voice over network (VON), this new technology relies on packet-oriented digital networks to deliver voice communication services as a digital stream. By sampling speech and recording it in digital form, encoding the digitized speech into packets, and transmitting the packets across computer networks, VON systems offer a lower cost alternative to PSTN due to their inherent efficiencies and lower bandwidth requirements.
Several communication protocols are used to deliver packet-based VON services. They include voice over the Internet Protocol (VoIP), voice over frame relay, voice over asynchronous transfer mode, voice over digital subscriber line, and voice over cable.
One issue that arises in VON telephony is echo cancellation. Poor echo cancellation reduces user satisfaction. Typically, VON network service providers implement some sort of echo cancellation on the packetized data. However, for the network echo cancellation filters to converge effectively, some degree of preliminary echo cancellation is useful on the unpacketized data. Such echo cancellation typically is done digitally by the interface circuit prior to generating an analog signal for transmitting over the PSTN. Generally, an echo cancellation filter is employed to reduce the echo. The filter typically has multiple taps, each with an assigned weighting coefficient.
Echo cancellation using a least mean square (LMS) technique to set the filter coefficients is known in the art. However, this technique places significant processing resources on the interface circuitry, thereby increasing its cost.
This section of this document is intended to introduce various aspects of art that may be related to various aspects of the disclosed subject matter described and/or claimed below. This section provides background information to facilitate a better understanding of the various aspects of the disclosed subject matter. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art. The disclosed subject matter is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.